1. Technical Field
The present invention relates to a photographing apparatus having the function of preventing the blur of a still image and, more particularly, to a photographing apparatus which can prevent the blur of a still image in photographing the still image by embodying a mechanical shutter function with an iris meter.
2. Related Art
A digital image apparatus, such as a digital camera or camcorder, photographs an image by sensing light reflected from a subject by using a photoelectric transducer. The digital image apparatus stores the image in a memory device in the form of digital information so that the user can edit the image by means of a computer.
In photographing a still image, the digital image apparatus uses a mechanical shutter to reduce shaking of a screen due to movement of the subject or shaking of the photographer's hands.
A digital camcorder consists of a photographing unit, stepping motors and motor driving units for driving the respective elements of the photographing unit, an analog-to-digital (A/D) converter, a signal processing unit, a memory, an image chip, a pulse generation unit, and a control unit.
The photographing unit includes a zoom lens unit for adjusting the magnification of a subject incident on a photoelectric transducer, a mechanical shutter unit for preventing blur of a photographed image generated due to shaking of the photographer's hands or movement of the subject, a diaphragm unit for controlling the amount of light incident on the photoelectric transducer, a focus lens unit for controlling the focus of the image incident on the photoelectric transducer, and the photoelectric transducer for converting the incident light into an electrical signal.
The zoom lens unit, the mechanical shutter unit, the diaphragm unit and the focus lens unit are driven by respective stepping motors. The respective stepping motors are controlled by the motor driving units operated according to a control signal from a control unit.
A pulse generation unit outputs a charge extract pulse for extracting charges accumulated in the photoelectric transducer, and an erase pulse for erasing the accumulated charges. The A/D converter converts the analog signal from the photoelectric transducer into a digital signal according to a correlation dual sampling process and an auto gain control process. The signal processing unit encodes and compresses the digital signal. The image chip generates an image suitable for the photographing apparatus, such as a digital video compressor (DVC) and a digital signal compressor (DSC). The final image is stored in memory.
The control unit controls the entire operation of the above elements. In particular, the s control unit outputs a control signal to the motor control unit for controlling the operation of the stepping motor connected to the mechanical shutter unit, thereby preventing blur of the photographed image generated due to shaking of the photographer's hands or movement of the subject.
However, the size of the lens is increased to compose the mechanical shutter, and special stepping motors and motor driving units are required to increase shutter speed, which results in high production cost.
On the other hand, in order to overcome the foregoing problems, it has been suggested that the mechanical shutter unit be removed and that the close time of a diaphragm be decreased by adjusting elasticity of a spring connected to a rotor of a diaphragm motor.